SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a130054fba5501d2a8c645974052727aa551335cb89ececb9a061c52c1ac81fd' 
  AND token = '344sr2KfDOaCJhDHy2sBmweyWkBvpws+yPksQwWdTDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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