SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7781126bc8203ee3749a644bfd264768ffceebf5ec076a29b9412dd1bfea03bb' 
  AND token = '43yc3MEJ42jEdY7I+rH2McCH+KlWgu8KHZXFSlVi3uY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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