SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6325f716b63eeaa08579bf1564d287a231bddd349c1cb9bd1dad86ee4f01d232' 
  AND token = '5jm5v3HfPUGx3S3xV4UYahuD44HSI7jZ2FED2wzw+yU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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