SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6fce48fd721d216ca642cd09b67288bbedef37e8c888fbc7de2c5cfb1653723' 
  AND token = 'AmrF5z8Zdt41aYSpY93P29GujNmVpA/keTr+WyPnJJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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