SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14b61837ddea970093720eded1825b5e7f5062ebd86aa704c91aedd63b5c13ac' 
  AND token = 'DnGZiIaYnBBbOZoq8Tl3YUK9ChU7kemU00IkhaahwFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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