SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20dcaa59d4a310cbb5664b746d61b6b9d426b890c96e625002ae1b557c0526e9' 
  AND token = 'k6EyXaQIb0w11on11biwuKeL+DXzG9cQLNcul8IYSMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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