SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '136363e121f6209a5d41d1ecc97276525fde77e8dcea2218986dda8f5a7da906' 
  AND token = 'l/E5dAXcKDpziflZzw3diiDkWanKe8LMxxDjfHHFYQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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