SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dabe99e1a44601fff727ab10f9a042123e758258e1d0219a06e658098452339' 
  AND token = '46IPeb4fxM6wBg/LdhEcwkwlGBgIvv74U6E4DCWg2ZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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