SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c673258c8f00cbb259b72dd2ff779a560aede0ebb5804b0a8643312d456347e7' 
  AND token = 'HbBzcDN1WvgRz2qC61tUhEvS+EUATZDq8UM+qYrAlJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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