SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7938a41d81960a796d97d3aa615c0a9a4994708cc228b026a70b604f040d8da8' 
  AND token = 'RXdMEBV58+lM3m86v8UPi4EfD0wNhO02gSgZENA8/nA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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