SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64343579fd34775d95b28a80afd5a661688578ba5c15bca632d6d262252a3bd3' 
  AND token = 'hG6y7htO1ThY8ruFz2t4PqKRIsmCyNgLAHCxcwihBD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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