SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ef5f956f64c72a2e06e279474088439372f0dfc64f4e998b7a842622b7e1309' 
  AND token = 'FeKnrtJcUnpdcENwoIO2i+vKIqvj9A6Z1zLxujHoBVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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