SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3576171b012573a4c58d0c880e49cff37a4fad639908b0343b705bcd291b7af8' 
  AND token = 'qaJONUx2fcxK6hqQgaSWajkxZO+w07WvTIIE/XVB9NM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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