SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '871e4ba4fbdea472335686749babffe795ff479423341f9b113c848480c2546c' 
  AND token = 'eaYnl9QNZ0q5zBYsdJbmpea05TiZz9AhV+8by2W7Qw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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