SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391d2dcf65c24a92050db4df1f564b25cc6e79128a3d3b2f9692c142aa497673' 
  AND token = 'ixF+KKojq3NgZFR+/PchuMI0mL7IFy7BgIg5N6SegCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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