SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5298539543499e7292492fc833e3fda6bff367309b182c5b1d47378772bc793e' 
  AND token = 'xbDmqBO56zXl1mg3K64DEohZu/S4Kc596PxVrd71Vcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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