SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1eea9c9a0c719a9738edd2d8d7ba0ae22645086504664a1d3a82b35fd204f448' 
  AND token = 'v4cWmtetZ4+QmI1MY6b9BmUs9BZ4ab/Z9Mw8pd9HjeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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