SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db2d847ff4ce3b10837cc19bd39c44ca9b8bd89485395ecc49a55badc15504fe' 
  AND token = 'r/eRMfyGJ04h1UwmIYOWFXR5Qleuc2b52EJ6GP325h0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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