SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ec81cb7e32d80306ac8b455112a861b790608ead69dde3ec84abe505f21370c' 
  AND token = 'CQes90MQ6kvfjzLTkvnL94EhTg6c1U0FLMp5fuHgxvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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