SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '31bba8cfd08ccfc4c679cf5b03c6bf2534102616032212c7e66c9f19c5cbd9f2' 
  AND token = 'mjVr4Gq9HPltEnG7Dvj+VlOEz5SeJ0UOgQtxqqzZ8hQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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