SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b258c342f9564209e8df1c0d917b963cf15550e0f49ad0635873e650a073777' 
  AND token = 'bSe96yHHnCqF3ChzXsRnjgKO47c4Q2YVbuhExYiRdLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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