SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f217c1fd3e9ba4dc0798e254f73a84289446c7fecd04b9795cc72b911f896ce7' 
  AND token = 'PCtFSKbEqh3UZF+JOUZKgVpO2Dk5LfMyXOE9V8ItGmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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