SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad394ddd51aec3f9795869ca5ba9c42bf9bc6619110dc6798b20553e548a0c57' 
  AND token = 'bPFgw8GwfRUlNZwbUGsN2RfW4C5SlgnMhCwRUqrQlwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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