SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '519d5b28d0756e3df33d510524765fa45579a9ed602ffc2d547cf29e84c36f6c' 
  AND token = 'DuCzOOxAxhZuTmZoUXNzrqGNw+RU7Wa0r0jwwzK0c4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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