SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70813cef14c2532fee0965e0757491eca9eaedd82e4d3e565161b5393ee75b75' 
  AND token = 'm432J+ihTaZnetb7KLiTKf16MsvxC7xWbzJHYNAMrqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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