SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae8112458ca6b13cfb5ef9f242baf2c567a0778a8b98dfaccc9ff7efc9c8e4b8' 
  AND token = 'j7tEwOnKvoFBBaWFzrD2eH/7xFbjMgVVg3UbfrGpHb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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