SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '849b9dc899013f005fb757a06f31b401e3c3a0d1f9899134124ee8e5bff348f6' 
  AND token = 'JtymypW6xgHPk+iE7B6XVg7XnRm3F8p+5JhgJhArF0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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