SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d63b176c4c10a689331372d85b7a52607dc006bc3032710bc0edd3de91a78a4' 
  AND token = 'kPQufPWICQGUxiNPlWvZ1aPzq3sM/3kjUH0juf29P18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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