SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '138a766a08fd2d10aec0e03fd2b455171cc50667edb88c53070ca10192b6badf' 
  AND token = '97Gk7hFSHfSksbW5rWkh8Kdn2reHHCxrapU5znvAKi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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