SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0e40af23e48383205911e2815bf4f3947b610488ce976873d7e65dbb7e39b95' 
  AND token = 'nCUdcz9HV3bbeJ9W/2ZdAxZsnk2iUGh6gcv+CCvwaKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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