SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03dd57db630bdf1ceffffa694289a9531969fc1a5c405b7bd88e671413733e27' 
  AND token = '6ejfANVy/Kk+tEbVfkl2Q5lWMGsYohY8pZzFNpdYMtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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