SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87b5496ce344adb5abce61793055c866f7bcd5a4baf8ffd751886b46d9830148' 
  AND token = 'mg2dBKurJXtzCHrFxmV2NMWWbBPm3ng5QomYGA/fL1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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