SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6293098be5c37f1d59047e62efdc6211483a011e75bb2e0c20fea6acf0862c4c' 
  AND token = '+UxS2zdNwlmRwn2fEigHBHNXvQalEynCiFYX0NGDYmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}