SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91111978e2c67524b50ea5bbf4cc09bfeb34d5f2d1abbdb730e7b2dcb5b988f2' 
  AND token = 'VxLnvYMcJU1CrU07lTt9VH9joLzcnsRM/OxEd3NsFUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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