SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bc73c9d0bfb5579b18def0a93da469c9347b6bfaa0b21f872e9418f77754ec1' 
  AND token = '8vvllodikmT1rmK6UV4OSyLFC32rKWNywFuIYSbJSKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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