SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11d2608ac6669c5e33956298e8b4280bbd723f70370a992705544f74d2bf4272' 
  AND token = 'aGdvQHwb6VzB8I59vAdBUHZwDv+Xlat3a02r6bu3YQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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