SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '783b46ce2f2970cdcf82c4e3b5e8affd5b1d815e0682d42e46eb8801ab87517f' 
  AND token = '5sXEfF0I3U+fVDWelnn3Mnqt/EGf/FNPgyI1RSt2dVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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