SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dceec902da7ae9b907848a80a0339134cf94378a1cd8263850751057616d437' 
  AND token = 'hIXzEfuaRIZ09j0a1TBmlA/EaqwNcVa0tF7poffwqOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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