SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85e260b62e0da333916984487b16b2f6224fd81c920921c4ff03fc8a6286897c' 
  AND token = 'fU1UQ3B4r4Ttvm27qj3gS6GJs/dYhZUQ2cs+kMZi+sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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