SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e9de43d348c45d4580752cbd3900ec775e192f57f96b73f5ae8521d3367df817' 
  AND token = 'H3S6RVv3htikK5/FQzZdYvkqGj4pboN8X8FyJhcrc5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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