SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27b91470140360a2dfb4eca894435117e9a4c977725d8ad3f268818872980214' 
  AND token = 'csqKVEL+v6vLTUyHNEQXiK5bQR5kGmQFpTZm5fGE/GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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