SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82e2dce5f7db01d4db1c1358d49f96279564aab5904ba8c97ea15a05b2113074' 
  AND token = 'rGr/ig+eVZvISltv0l87U79ZoHpjUHeqnRYpLxBZWj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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