SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f68aa64208850e85baf3ddc19a2f595682990bfe0310b4bcffbdafbdbce12d0f' 
  AND token = '3dhI7dNsGFgdcg0o2J4AKhHfq0NV8vOnbAXAZ2Pt8Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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