SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29dc7d8f2edce749e008e4d629ab0deec618ecc35036feb63eebf1e592a493f2' 
  AND token = 'R/VPQ7Usk79aRmEjhXwOs4uqToqnhnLur+RtsvNpXls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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