SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46f6b6e73ff347083213d304a32367110e1fbbd499f94e366b2c6e999fbe30ff' 
  AND token = '+pSJHUCqPrGwmOZcXKK52PsuardMmgXIDYzeH+fYLmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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