SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39caa6e8f46825b754db25136ca088040ee7f989d650613b4b039a1e40d31971' 
  AND token = 'N50X41/u9UJn3VwDGexLuKA11BbAJVOOX0NZgPOoDLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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