SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bea21715e82835ef95d4e305ac08e4b3ab08886adee3a08d47c53f6e98778133' 
  AND token = 'r8f2lxF2L5WyOO3hyERYajEM4mFZaN1rMSs8TLnvCtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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