SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a7ed83955500b42f7058d330f646016424c5b66f58dc43f3a04292846ce5472' 
  AND token = '5uQ27BYieFUUP/07mwxAjWMo3WfyV7JALHFlSyb+m24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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