SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47d90f92fc2a59f8028c81fc623d55720aa6260c75b32e15388e504a4a113ce9' 
  AND token = 'iAjJ9MnqPZ38GqaZgg4uXHpehgDZUYQ8MVOcFs7uUz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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