SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac0304d16d4af9c4c2ff3857bb6f64a689a3d31fbe957aa326f0b387629c4c57' 
  AND token = 'Cj75yVvvqCUCutF4bcg4Cqnrk6KjQ/9mtUHmek+UGaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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