SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed391c8324f1608bb618623efe449287dab68793abaf67d238b6f05e2d2f018e' 
  AND token = 'F1cQK6zPEJvDlxZTwYCXnwz4lmttZXzSh0ZsRW3zysc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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