SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2831f277d4b3297aadc1d003963d871e20b3069e3dfc750651a33bb56168a1fb' 
  AND token = '+6FW/NXMYUcIZi2d57BpUr7/vV3LzpVybT4H9cmUwZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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