SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '547fcd586e893274aff2c7aac8648abea37176b553558f54e24f8452dcf8ddea' 
  AND token = 'FAdWYwnMf8ycZ4iWOX7Z5sHBPGWuZdQmnBrWA/IN1EE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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