SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90f9c00fb7cf2c801326a2fa4fff79134689f4f24eb3610380e4c7957b1c96d1' 
  AND token = 'S5mtjEKznQSPM+aYcmtGFhYnZqG+3V5yI84dFH9Rqr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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