SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c99d3aa201095907a4f4526e1c413fedbf6c0af6c3fab1d13de9f79547f4ee43' 
  AND token = 'Sqb+EEoEU11MWbSMU4W55LfYYTl6Ch0bco9hErY2jhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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