SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4bb789b8bc52ef3bf11195238a2f5e3208aacdbcf3a341ca2f031d046a0c0ada' 
  AND token = 'WnCZUGeg3JmxRNr/By4/iCOeVGMD7ko+QUOVtF2jrYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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