SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9638b54f0e5bf7a8eca904146d2f1fb968fadef5ef3206576906cbda0d19a564' 
  AND token = 'JX7IObFzaYqTkvZpNYmzPkXDiTPXqsXRUcDfHBNzIBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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