SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a373d5b77fc0812ddf94064004094f1fafaa00ca31dcd064fedae4311673acdb' 
  AND token = 'xlYvZ1PGiOzxS7e5ZLZtkSy7do4flGjkJVl2T9giYOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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