SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de84ffc52a7239b7c9f243fe12a3b22ffe7e44128458573e411b656e329a7c6f' 
  AND token = 'GVXNhUUanHPJpNlBl0cjznkIVsAlzvRCogLkzqA7pWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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