SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75802b0d6097f8edae1ac1c6729b39c554d3928e7e9956aff27db59f921b56c2' 
  AND token = 'H5K6FWWHwoGo+6qN0nwM3lSkwBRwfWsCjtDim/cV1zk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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