SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '710913f623460930f99da6bb2fd39c0dd2b1c9f9a40e5808fd6986297842a886' 
  AND token = 'xwDLQIKnNcNgBhNrxLL8pLi6YPQu0F/RzpXpvfaMPd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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