SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b99ef78e9003c577d05bfcc636f9570baf0bf74995c679207ea9174ce622df40' 
  AND token = 'zQ4K6bB9thfOxNJ92yQOie8pgEiW9AQahCueCqYYuVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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