SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c378e0d4e76f73070743d1661cb5d9d313c794c50ec6c2196fdeac1017dd6f8' 
  AND token = 'mf9ocs/KSgzWu0G2vPZI2g9RqXTAj+UW4+Hn5GHiYeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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