SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3b2712235bc472771af00ba43876f2590fc8a05e447336e4c0859788881ad5a' 
  AND token = 'ATi/yqNalgrFy5Dv+dCXKKKd4vZYARjmwrdJsKtmvOU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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