SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea3e33338ef63d01f61b3215598899752139ab407976f21e3433d848a1f50575' 
  AND token = 'OnDZrm6ZPW/Pgt9svwb1eHpwxYnGfNjFD3OZ9vFJiCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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