SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3941410c70ab606b39f7769971fb3900f267e9b109442734bfa715643e172eba' 
  AND token = 'Cgrj5TMpjlcTeiB7NHqD4nHWdWqwPwPw489uzkuPU54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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