SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '481578f2acc30d552237282718058e517b5697512a77ce855064baa42bd2bd75' 
  AND token = 'l1oip0gK3gF0XECLCNBSurPxrPkYyAyh9+W+MFweI3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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