SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '628c706c4af66407841eeda9f5e03018947320272821f31766adf186a6e94a23' 
  AND token = '8UJWBjFuVABzV6GJCkVkUovpDEb3cHmR2ROsgEt3nQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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