SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0be3da4da5421b8bdcf755de05958c0c97fbade6ca0f0188a7b7b58970aa2f7' 
  AND token = 'QvYLw4GBGWlRsu61SiI2xlhIXDYHCSNHa3LdnYsGYHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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