SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecfb664283724c632ec6281a9cfcf618c36b921d2234236e7898e7bca13dc249' 
  AND token = 'IsW07g549BURD2QsbmdGTPKrtsnOccNjsY3NIh/LiPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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