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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85cc80dd723137b3237b67910e4a5c4975ba4f8df031d24ea6d37f9f9cdc5d42' 
  AND token = '5lBgdV7P5OZOIMbGXFlsdd9z4uRZggegBT9QeYY+2PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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