SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ae860866a0fddcf39632034c48ff0992033d265a8004f220ea4dd984caaabba' 
  AND token = '4sRsVWd66A6nXZ9QW9xvTJIVghLEXdUFyVC47UaSdZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}