SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a1e198c817c0ae46793a07044dfe259175927fd4f15180d070915c7343ff737' 
  AND token = 'UOXt6lXIVMTTUuBQicx+fohvYHdrUKr0HMkm7GmmDbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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