SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '577e1fd3e0c08e8eeefa2c2aa86b3101b3992b808265f064488016b819923735' 
  AND token = 'M+/+LYMatucG/yYMJi6kKiaTQZcxRiHvCunSh/u3eho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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