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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b73c1730fb0b36922a8f1c75ef57dcd7a631c457e1bf9183cc4ad03f7c33972d' 
  AND token = 'W3LrBbBqcSsKqlLqLfvW7O/AINBlpemQugw8zmpgCY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}