SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d515cf6979066f9a5edfd70cdafe3423ec3bd09161e6192c92b0e3804cf6c87' 
  AND token = 'mUfvB8S6vYKpWY29Qd/kU1qxfIeFgPg7qCIhOGAIjtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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