SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6dc64a5a82d556812b934ddc2999b0fd9c0d6c76101fb1547f773de600c6309' 
  AND token = 'LEczZwMywyl7VPJGIsue6pKObriN3OCJJ770SEl2sDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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