SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2ff2d3e4788e013c656ab2c6841b58438bcd86f769849ebba9722b1d1431400d' 
  AND token = '3c2Tow0SRkz0aXp+TUgKZAaUfwcxbl0vEDWbYINV8gA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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