SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a82c88fc219bdef888736f6dc2fdba54c1d3569301d77994654aeeefa2d57267' 
  AND token = 'PJU/upo61PeZynTP3DciHXII0RkA9cg2stQiTULL48c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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