SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3726405c19d013148651fe21d421d20510ee16435a7aef52e260e7a207d6c918' 
  AND token = 'aB+ji5G638vwFahojXl84fot5d0VibQSiARGPWvDMHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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