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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e3ccebf534f61aa8cfa4c0a08d00a7d0d6cb89703d2a8b08508386c5a12dd4a' 
  AND token = 'GPmu7fVur4jtkMcf77FE7vvA3mB2pYUEk/ib9aQ6xgs=' 
  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"
    }
  }
}