SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b30ea8e409ac3259c57620c4a0e83b266721baddfce648a7a34d891943e583' 
  AND token = 'HoT2L4sM5OXf8DhcnopHnHsed+EtJY2YIcxJdN6INaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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