SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '243953dfc01cb7c7ba4a74227dff88af3f89896cb139ba9d92c2fabc8218939b' 
  AND token = '6VSzhC/R0wInPQ+JfzHpKTz/Ev5Dx1wdpKmPcx4p4mI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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