SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19f4f407489d3ce8851cb1976d9537fa4685ee06abb048ddf15d622b87b6280a' 
  AND token = 'zt+lxyaGgNjUnNHJmEf9uq0DqK6lTHYU2Z91impqLF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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