SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'decdb16593a108430cb65f6645164037abb75c020c61fdc7c92e89e1264d781a' 
  AND token = 'dZCPlii7FkldIxU1bXd2qsWkblfxaT4ZWEMLlEiZpI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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