SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d787a53800321b3db2cd9af338425d7e68be45ce5fa895e1bba5dda04e01047' 
  AND token = 'sVzZ93DEFRPut+QKn8/DkpbrVW0JEc8GcHgLTj6e8wA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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