SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0df2380d14f71420f9a765359c3753894d2ae628a93904442f4a333e961b7550' 
  AND token = '1MK6BKOCiipDahyvcvk/ZFhwaAzClRhMkzzGTOBCmB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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