SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe8f488c1c43b317f6afc9c13df26575277c4f26684a8202935ceb77dcb65af0' 
  AND token = 'DNzH+oUvd1sDHiZzpgdpo9bfnrBVND1naCrgk/TI9+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}