SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '965d3cd29e75d86505771896652565053d2ce80d3f9bed72888a4d7672473bbb' 
  AND token = 'aownGIhvtFUHJqAVsXKBqqgb0HcVi/8NbSxb/zS/vVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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