SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3307af5581da18f9697a9978343b07141bcaaea73e88a7571f847b9e0b8794ac' 
  AND token = 'cfqMsFQ/bjmJGMoVg58f4BXBwS/VZ4k/KOUrlbd5Eco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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